Many types of digital devices send and receive digital information streams. Such information streams can include video, audio and/or data, in original or compressed form. Each information stream includes at least one Elementary Data Stream (EDS), and often a plurality of EDSs, which when multiplexed together yield a Composite Data Stream (CDS). Often, one or more of the EDSs has a Variable Bit Rate (VBR), causing the CDS to have a variable bit rate. In practice, many transmission links, especially medium and long haul links, carry data at a Constant Bit Rate (CBR), even if the data originated as a VBR stream.
A composite data stream transmitted across a CBR transmission link undergoes processing at one or more receiving devices located at the far end of the transmission link. Many receiving devices often process incoming data at a variable rate as determined by a synchronization process implemented in the receiving device. At the outset of synchronization, the receiving device will de-multiplex the EDSs from the CDS and buffer each EDS. Thereafter, the receiving device will decode a time stamp within each EDS and then present the time stamp for comparison to a system clock recovered by a Phase Lock Loop (PLL) from clock references embedded in the CDS. Assuming a match between the system clock and the time stamp, the packet then undergoes decompression, if previously compressed, and thereafter undergo rendering. Such rendering can include display by a display device, or subsequent processing, such as by a CODEC. The embedded clock references and time stamps constitute control data that provides synchronization among the all of the EDSs in the CDS.
The synchronization process described above determines the processing rate of a CDS having a variable bit rate. If the receiving device processing rate does not correlate with the CBR of the incoming CDS and no adjustments are made, then data can become lost or corrupted.
Thus, there is need for a technique for sending data having a variable bit that will minimize loss and corruption.